Concept of using external GIS files in the Application

The method of spatial selection internally within a MS-Access application and not externally with ArcView was first developed for the DVS (Digital Visualisation System).

It requires a GIS Plug-in (MapObjects Light 2 from ESRI). In order to require the desired functionality, a special data-model was built. This will particularly manage the following aspects:

GIS files to load for each model

Appearance of GIS layers in the map (legends and labels)

Functionality of GIS layers (suitable for selection or only for display)

Fields relevant for querying

Additional functions that are only relevant for the DVS application (functions not relevant for the preprocessing module are stroken out).

Understanding this data model will enable the software developer to change the GIS layers in the individual applications as well as their appearance and functionality. This is not done by editing the programming code (VBA) but instead by the entries of data tables contained in the application.

There are 3 data tables required, their relation is shown in the screenshot below. (Click on the tables to go to the detailed descriptions).

Subdirectory where the shape file is located. The part of the path of the shape files which is common to all, is given by the configuration file preproc.cfg.

SFName

Description of the shape file as to be shown with the selection button. It also is used for the generation of the Excel chart title.

CodeField

Name of the field containing the code of the shape in the shape file's database table

NameField

Name of the field containing the name of the shape in the shape file's database table. Code and name may be identical if only one of them exists.

SelOutputField

Name of the field which will contain the code of the shape file in the output selection table. The contents has to be different to NameField as in most cases both fieldnames will be used for the generation of the selection table.

IntersectCode

Intersection code

LabelThreshold

Threshold when labels (names) should be displayed on the selection map